Elastomeric bladder assembly

ABSTRACT

The bladder assembly of this invention has spaced apart inlet and outlet means and the bladder is capable of expanding and contracting radially and axially upon inflation and deflation. When deflated the lumen of the bladder is substantially completely filled by lumen filling means, which in a preferred embodiment, protect the bladder from being punctured by the hypodermic needle used to fill and inflate the bladder. The lumen filling means resists the compressive load applied during insertion of the needle and maintains the inlet and outlet means in spaced apart relationship while providing substantially no resistance to the axial expansion of the bladder. By having the lumen of the bladder filled with the lumen filling means when the bladder is deflated, before its subsequent inflation and deflation, substantially complete expulsion of the fluid contents of the bladder can be obtained. 
     The bladder assembly of this invention may be particularly adapted for use in an infusor for dispensing fluid under pressure.

RELATED PATENT APPLICATIONS

This application is a continuation of our copending, coassigned patentapplicant Ser. No. 113,224 filed Jan. 18, 1980 for Medical Infusor, nowU.S. Pat. No. 4,318,400.

TECHNICAL FIELD

The invention relates to an infusor for dispensing drugs in liquid formto a patient.

DISCLOSURE OF PRIOR ART

The infusor in which the elastomeric bladder assembly of this inventionis adapted for use was developed as an improvement of the infusordisclosed in commonly owned U.S. Pat. Nos. 3,895,631 and 4,140,117. Theinfusor of those patents involves two basic components: a replaceablecartridge assembly that is designed to hold the drug within an elastomerbladder; and a housing into which the cartridge is inserted. The housingis shaped to fit on an extremity of the patient and it contains anadjustable flow control subassembly. These patented infusors performedsatisfactorily. But, they are complex in that they are composed of agreat many parts. Accordingly, they cannot be easily manufactured in anautomated manner and are thus costly relative to the conventionalgravity-feed infusion apparatus used in health care. In addition theseapparatus are not adapted to be filled by ordinary hypodermic syringes.

DISCLOSURE OF THE INVENTION

An object of this invention is to provide an elastomeric bladderassembly that may be filled with a fluid using a conventional hypodermicsyringe.

Another object of this invention is to provide an elastomeric bladderassembly that is capable of expelling substantially all of its fluidcontents.

Another object of the present invention is to provide an elastomericbladder assembly adapted for use in a compact, lightweight infusor thatis less complicated and easier to manufacture than the above describedpatented infusors.

These and other objects of this invention will be readily apparent fromthe following description with reference to the accompanying drawingswherein:

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an exploded, perspective view of an infusor utilizing anelastomeric bladder assembly according to this invention:

FIG. 2 is a perspective view of the infusor of FIG. 1 with the bladderof the infusor filled with liquid;

FIG. 3 is an enlarged, sectional view of the infusor of FIG. 1 takenalong line 3--3 of FIG. 2;

FIG. 4 is an enlarged sectional view of the infusor of FIG. 1 showingthe elastomeric bladder of this invention ready to be filled with liquidfrom a syringe; and

FIG. 5 is an enlarged sectional view similar to FIG. 4 of anotherembodiment of the elastomeric bladder of the invention.

DESCRIPTION OF INFUSORS SHOWN IN DRAWINGS

FIGS. 1 and 2 depict an infusor, incorporating the bladder assembly ofthis invention which infusor is generally designated 11 in the drawings.The infusor comprises: a tubular housing 12; a plug/flow controlassembly 13; a piston/filling port assembly 14; an elastomeric bladder15; an end cover 16; and a delivery conduit 17. Infusor 11 issymmetrical about the axis of housing 12. Its manufacture is thussimplified since no radial orientation of parts is required during itsassembly.

Except for the delivery conduit 17, the elements of the infusor arecontained within the lumen of cylindrical housing 12. Housing 12 may bemade from various thermoplastic polymers. A graduated volume scale 18 isimprinted, scribed, or otherwise applied to the housing wall. Asdescribed below this volume scale indicates the quantity of liquidcontained within bladder 15. It is graduated in milliliters from 1 to 60ml, the capacity of bladder 15 being 60 ml.

As shown in FIGS. 3 and 4, plug/outlet flow control assembly 13 is fixedin one end of housing 12. The fixation may be effected by adhesion,fusion, or other appropriate means. Assembly 13 includes a main body 19and an axial post 22 that is integrally connected to the inner side 23of body 19. The body has a peripheral shoulder 24 against which the endof housing 12 is seated. An axial bore 25 of varying diameter extendsthrough body 19 and post 22. Bore 25 serves as an outlet port fortransmitting liquid from bladder 15 to delivery conduit 17. Within bore25 are a cup-shaped particle filter 26 and a capillary flow controlelement 27. Filter 26 and element 27 are compression sealed within bore25 through the use of O-rings 28 and 29. O-ring 28 is seated between ashoulder 32 at a diameter transition in bore 25 and the inner end offilter 26. O-ring 29 is seated between the outer end of element 27 andthe enlarged diameter inner end 33 of delivery conduit 17. A thirdO-ring 34 forms a seal about the perimeter of the interface betweenfilter 26 and capillary element 27. End 33 of conduit 17 is fusionsealed in an enlarged diameter segment 35 of bore 25. End 33 (and inturn element 27 and filter 26) is held under compression by adisc-shaped plug 36 that is fixed by adhesion, fusion, or other fixationmeans within a recess 37 in the outer side 38 of body 19. Plug 36 has anaxial opening through which delivery conduit 17 extends.

Piston/filling, inlet port assembly 14 is slidably housed within thelumen of housing 12. It includes a head 42, a base 43 and an axial post44 extending from the inner side of base 43 toward the axial post 22 ofplug/outlet flow control assembly 13. Head 42 has an end wall 45 thattraverses the lumen of housing 12 and a cylindrical side wall 46 thatextends laterally along the inside of housing 12. An axial bore 47extends through end wall 45, base 43, and axial post 44. Base 43 isaffixed to head 42 by adhesion, fusion, or other affixation means. Aseptum 48 is contained within a recess 49 in the outer side of base 43.Septum 48 is sealingly compressed at its perimeter. It traverses andcloses bore 47. It is made from a material, such as an elastomer, thatis capable of being punctured and resealing itself after the puncturinginstrument is withdrawn. The outer side of end wall 45 has an axialprojection 52 with a conical recess 53 that opens into axial bore 47. Asdescribed in detail below recess 53 acts as a guide for the instrumentthat is used to charge bladder 15 with liquid.

As shown in FIG. 4, when bladder 15 is deflated (not filled) it fitsabout axial posts 22 and 44 in sleeve-like fashion. The outer diametersof posts 22 and 44 are not greater than the inner diameter of bladder 15when it is deflated. Preferably the outer diameters of the posts areslightly smaller than the inner diameter of the deflated bladder. A pairof spring clamps 56 and 57 around the ends of the bladder effect fluidtight joinder between the posts and the bladder ends. The axial posts 22and 44 substantially fill the lumen of bladder 15 and their free endsabut each other when the bladder is deflated. As discussed below, thesefeatures contribute to the complete discharge of liquid from the bladderand the ease with which the bladder may be charged with liquid.

FIG. 4 shows the infusor ready to be charged with a drug in liquid form,designated 58. As shown, a syringe 59 containing liquid 58 has beeninserted into the lumen of housing 12 with the needle 62 of the syringepuncturing septum 48 and extending into the axial bore 47 of assembly14. In this insertion procedure recess 53 guides the end of needle 62into the opening of bore 47 and the force applied to assembly 14 topuncture septum 48 is transmitted to fixed plug/flow control assembly 13via the abutting posts 22, 44. Piston/filling port assembly 14 is thussupported during this initial step in the filling operation. Further,post 44 guides needle 62 after the septum is punctured and shields thebladder from being punctured.

Once the syringe has been positioned as shown in FIG. 4, the plunger(not shown) of the syringe is depressed to eject liquid 58 into bladder15 via needle 62, and bore 47. It should be noted that there is no sealbetween the free ends of posts 22, 44 so that the liquid is free to flowfrom bore 47 into the bladder. It should also be noted that the conduit17 must be capped, valved or otherwise closed off at this point in timeto prevent the premature dispensing of the liquid from the infusor. Asliquid is ejected from the syringe into the bladder, the bladder expandsaxially and radially until it assumes the expanded (filled) statedepicted in FIG. 3. The volume of liquid in the bladder may bedetermined by observing the location of an indicator line 63 in wall 46relative to volume scale 18. Housing 12 is transparent in the area ofscale 18 so that indicator line 63 may be so observed. Piston assembly14 slides axially within the housing to accommodate the axial expansionof the bladder. As it does so, line 63 moves along scale 18. When thebladder is fully filled, line 63 will register with the 60 ml mark onscale 18. When filled the bladder wall is spaced from posts 22, 44except at the clamped ends and a radial air vent 64 traversing post 44is exposed and unobstructed. The bladder wall is also preferably spacedfrom housing 12, except that gravity may cause a portion of the bladderwall to touch the housing. Such spacing prevents the housing fromconstricting the bladder.

Once bladder 15 is filled with liquid 58 the infusor is tipped into avertical position with the piston-filling port uppermost. This causesany air that may have been trapped in the bladder to rise to thepiston-filling port end of the bladder. The syringe is then withdrawnpartly so that the tip of the needle resides in the segment of bore 47between septum 48 and air vent 64 and any air trapped in the bladder issucked therefrom into the syringe via air vent 64. The syringe is thenwithdrawn completely from the infusor, with septum 48 sealing itself andclosing bore 47 to liquid flow. Filling port cover 16 is then insertedflush into the open end of housing 12 to prevent patients from tamperingwith the contents of the housing. Infusor 11 is then ready for use.

For use on ambulatory patients, infusor 11 will normally be attacheddirectly to an extremity with a strap accessory or to the body orclothing with an appropriate holster, pouch, belt, or similar attachmentmeans. A cannula is then inserted at the infusion site. The end ofdelivery conduit 17 is then attached to the cannula. Liquid 58 will thencommence to be infused into the patient from the bladder through bore25, filter 26, the capillary of element 27, conduit 17 and the cannula.The flow rate of liquid to the patient will depend upon the dimension ofthe capillary of element 27, the pressure exerted on the liquid by thebladder, and the viscosity of the liquid. At a fixed capillary dimensionand pressure, flow rate may be correlated solely to viscosity and thusmay be predetermined accurately.

When infusor 11 is exhausted, bladder 15 will appear as in FIG. 4. Theinfusor is capable of dispensing essentially all of its liquid chargebecause posts 22, 44 occupy the deflated volume of the lumen of bladder15 leaving no room for residual liquid. FIG. 5 illustrates an alternate,less preferred infusor, generally designated 65. It is similar toinfusor 11 except as regards the attachment of the bladder ends, thebladder lumen filling means, and the location of the liquid flow controlregulator. Since infusor 65 is similar to infusor 11 in other respects,only the above mentioned differences are described in detailhereinafter.

The basic elements of infusor 65 are: a tubular housing 66; a plug/flowcontrol assembly 67; a piston/filling port assembly 68; an elastomericbladder 69; a filling port cover (not shown); and a delivery conduit 72.Piston/filling port assembly 68 includes an integral axial post 73 thatextends nearly the entire length of deflated bladder 69 and abutsagainst the inner side of assembly 67 when bladder 69 is deflated. Post73 is an alternate bladder lumen filling means to posts 22, 44 ofinfusor 11. Bladder 69 fits about post 73 in sleeve-like fashion. Barbs74 on the piston end of post 73 anchor enlarged diameter end 75 of thebladder to the post. The other end of the bladder is sealingly seatedwithin assembly 67. Post 73, as posts 22 and 44 of infusor 11, functionsas a filling needle guide and provides support for assembly 68 duringthe filling operation. A filter and flow control subassembly, generallydesignated 76, is contained wholly within the body of assembly 67 ratherthan partly within an axial post and partly within the main body of theassembly as in infusor 11.

Modifications of the embodiments shown in the drawings and describedabove that are obvious to those of skill in the medical device and/ormechanical arts are intended to be within the scope of the followingclaims. Such modifications include, without limitation, other bladderlumen filling means such as a pair of axial posts similar to but shorterthan posts 22, 44 with a "floating" post segment therebetween or amultiplicity of spherical bodies, other means for attaching the bladderends to the plug piston assemblies, other bladder filling means such asradial inlet to a post aperture, and other flow regulators such asporous plugs, fiber bundles, porous films or known adjustable flowregulators.

Accordingly many changes or modifications can be made to the embodimentdisclosed herein without departing from the scope of this inventionwhich is limited only by the following claims wherein:

We claim:
 1. An elastomeric bladder assembly for dispensing a fluidunder pressure comprising in combination;(a) an elastomeric bladderhaving opposed ends; (b) puncturable, resealable septum means in fluidsealing relationship to one end of said bladder whereby fluid may beintroduced into said bladder through said septum means and; (c) lumenfilling means disposed between said opposed ends, said lumen fillingmeans comprising at least two posts received in and substantiallyfilling the lumen of said elastomeric bladder when said elastomericbladder is in a deflated condition, said posts in the deflated conditionbeing axially aligned in end to end abutting relationship and beingcapable of resisting axial compressive loads between said opposed endswhile offering substantially no resistance to axial expansion andcontraction of said bladder; whereby said opposed ends may be maintainedin spaced apart relationship while said bladder is deflated and saidopposed ends are free to move axially apart during inflation and axiallytogether during deflation of said bladder.
 2. The elastomeric bladderassembly of claim 1 wherein the port adjacent with said septum isprovided with a port in alignment with said septum and of a lengthsufficient to receive the length of a needle used to inflate saidbladder to substantially shield said elastomeric bladder from saidneedle when said bladder is in a deflated condition.
 3. The elastomericbladder of claim 1 or 2 wherein said axially aligned posts are connectedto said opposed ends of said bladder.
 4. The elastomeric bladderassembly of claim 1 or 2 wherein means are provided for maintaining theaxial alignment of said posts when said bladder returns to a deflatedcondition after discharge of its fluid contents; whereby said lumenfilling means will substantially fill the lumen of said deflated bladderand provide for substantially complete discharge of said fluid.
 5. Theelastomeric bladder of claim 4 wherein said bladder is received within atubular housing and said means for maintaining the axial alignment ofsaid posts comprises plug means engaging said housing proximate one endthereof and carrying one of said posts and piston means slidably engagedwith the interior of said housing and carrying another of said posts. 6.The elastomeric bladder of claim 3 wherein means are provided formaintaining the axial alignment of said posts when said bladder returnsto a deflated condition after discharge of its fluid contents wherebysaid lumen filling means will substantially fill the lumen of saiddeflated bladder and provide for substantially complete discharge ofsaid fluid.
 7. The elastomeric bladder assembly of claim 6 wherein saidbladder is received within a tubular housing and said means formaintaining the axial alignment for said posts comprises plug meansengaging said housing proximate one end thereof and carrying one of saidposts and piston means slidable engaged with the interior of saidhousing and carrying another of said posts.
 8. The elastomeric bladderassembly of claim 7 further comprising flow control means forcontrolling the release of fluid from said bladder assembly in fluidcommunication with the lumen of said bladder.
 9. An elastomeric bladderassembly for dispensing a fluid under pressure comprising incombination:(a) a tubular elastomeric bladder expandable from a deflatedto an inflated condition; (b) a tubular housing receiving said bladder;(c) puncturable, resealable septum means associated with one end of saidtubular bladder, whereby fluid may be introduced into said elastomericbladder through a hollow needle punctured through said septum means andreceived in said port, the void volume of the bladder in its deflatedcondition is reduced and the axial alignment of said bladder in itsinflated and deflated condition is maintained; and (d) piston meansslidable in said housing and plug means fixedly mounted in said housing,each said piston means and plug means being provided with a dependentpost aligned axially with said housing and fluid sealingly receivedwithin the opposite ends of said elastomeric bladder, the combinedlength of said dependent posts with their adjacent ends in abuttingrelationship being sufficient to substantially fill the lumen of saidtubular bladder in its deflated condition while offering substantiallyno resistance to inflation and deflation of said elastomeric bladder,the post received in the end of the bladder having the septum meansbeing provided with a port providing fluid communication between thelumen of said bladder and said septum.
 10. The assembly of claim 9wherein the length of the port in the post associated with the septummeans is sufficient to receive the length of the filling needle insertedthrough said septum, whereby said bladder is protected from puncture bysaid needle.
 11. The assembly of claim 8 or 9 wherein at least a portionof said housing is transparent whereby observation of the location ofthe piston provides a visual indication of the amount of fluid in saidbladder.
 12. The assembly of claim 11 wherein said housing is providedwith indicia overlaying the path of motion of said piston means.